Praise be to Allah.
Firstly: Hemp (also known as cannabis) is a plant that is sometimes cultivated for its strong fibres, which are obtained from the woody stems of the plant and are used in making string and various kinds of rope.
Growing hemp is banned in most countries because it is possible to obtain a psychoactive substance from it, known as marijuana or hashish. End quote from al-Mawsoo‘ah al-‘Arabiyyah al-‘Aalamiyyah.
The psychoactive substance in cannabis that has an effect on the brain and nervous system is that which the questioner referred to by its acronym THC, which stands for tetrahydrocannabinol.
Secondly: The percentage of this substance that is present in the oil asked about is 0.06%, which is a small amount that is negligible and has no effect, so it does not make it haraam to consume it, and it cannot be deemed to be naajis (impure) – according to the view that intoxicating liquids are naajis.
Al-Khateeb ash-Sharbeeni (may Allah have mercy on him) said: The argument having to do with using it – meaning alcohol – for the purpose of medical treatment has to do with pure (100%) alcohol. As for medication that is mixed with it and the like, which leads to it being completely absorbed, it is permissible to use it for medical purposes when there is no alternative to it among pure things that could be used for medical purposes. This is like the ruling on using impure (najis) things for medical purposes, such as snake meat and urine. That applies even if the purpose of using it for treatment is to hasten recovery, on condition that it is used on the advice of a Muslim doctor of good character, or based on his experience of using it for medical purposes. End quote from Mughni al-Muhtaaj (5/518).
Regarding the permissibility of using medicines that contain a small amount of intoxicating alcohol, there have been several statements from Islamic Fiqh Councils and fatwas from Ifta’ committees and councils in the Muslim world, whilst noting that it is preferable to avoid adding alcohol to any medicine, so as to avoid a dubious matter.
It says in a statement of the Islamic Fiqh Council of the Organization of Islamic Cooperation no. 23 (11/3):
With regard to queries from the International Institute of Islamic Thought (IIIT) in Washington, their questions are as follows:
There are many medicines that contain varying amounts of alcohol, ranging from 0.01% to 25%. Most of these medicines are medicines for colds, sore throats, coughs and other common ailments. These alcohol-containing medicines represent approximately 95% of this type of medicine, which makes finding medicine that is free of alcohol very difficult or impossible. What is the ruling on taking these medicines?
The Muslim who is sick may take medicines containing a percentage of alcohol if medicine that is free of alcohol is not available, and that medicine is prescribed by a trustworthy, professional doctor. End quote from Majallat al-Majma‘, issue 3, vol. 3, p. 1087.
It says in a statement of the Islamic Fiqh Council of the Muslim World League:
1 – It is not permissible to use pure alcohol as medicine under any circumstances, because the Messenger of Allah (blessings and peace of Allah be upon him) said: “Allah has not made your healing in that which He has forbidden to you.” Narrated by al-Bukhaari in his Saheeh. And he said: “Allah has sent down disease, and He has made for every disease a remedy. So treat disease, but do not treat it with anything that is haraam.” Narrated by Abu Dawood in his Sunan and by Ibn as-Sunni and Abu Nu‘aym. And he said to Taariq ibn Suwayd, when he asked him about alcohol that is added to medicine: “That is not a remedy; rather it is a disease.” Narrated by Ibn Maajah in his Sunan, and by Abu Nu‘aym.
2 – It is permissible to use medicines that contain negligible amounts of alcohol that are required to produce the medicine for which there is no alternative, on condition that it is prescribed by a doctor of good character. It is also permissible to use alcohol externally for cleaning wounds and killing germs, and to use creams and lotions containing alcohol for external uses.
End quote from Qaraaraat al-Majma‘ al-Fiqhi al-Islami bi Makkah al-Mukarramah, p. 341.
See also the answer to question no. 259044 .
And Allah knows best.